Cheryl has already answered. Just to add a bit of more information:
A WIKI remembers everything you do. Even though the data is really well protected from viewing, depending on your choice of privacy, it is still kept in the database and history is kept of all changes.
So in general for recent people it is better to input the bare minimum from the start. I basically only add the links to parents, not mentioning them in the bio, so only the tree is built. But nothing else on living people.
If you like to watch and listen to someone explaining it all, see the links on this page: https://www.wikitree.com/wiki/Help:Video_Help
It really got me going.